When To Treat For Grubs in Your Lawn

When To Treat For Grubs in Your Lawn

Grubs, white grubs, grub worms. No matter what you call them, these pests, when left untreated, can wreak havoc in a lawn in absolutely no time. 

Before jumping into prevention, and grub killers and grub control in your lawn, it’s important to know about the Japanese beetle and its life cycle. 

Grubs are the larval stage of the European chafer, June beetle (June bug) and/or Japanese beetle. These are the most common in New England. Adult Japanese beetles (June bugs) typically lay eggs in lawns in June. The ideal conditions are green healthy, irrigated lawns. As the larvae eggs hatch, they begin to eat the roots of the grass throughout the summer into the early fall months. 

As they eat the roots throughout the summer, you will find irregular patterns of brown patches throughout your lawn, and will be able to peel the grass back like a rug or doot mat. You will find the grubs at the edges of the damaged turf.

As the season winds down and the soil cools, the grubs move deeper into the soil to ‘hibernate’ in a frozen state over winter. And as soil temps begin to rise in the following spring, they’re much larger and begin to slowly feed once again. However, typically spring grubs do not do much (if any) damage to the lawns.

As the season progresses around June, the pupate emerge from the soil as a Japanese beetle, and the egg-laying life cycle process starts all over again.

Since these larger April/May grubs do not pose much threat in the springtime, it is a good sing to begin your preventative treatment. 

Controlling Grubs In Your Lawn

Prevent and control grubs by applying Acelepryn (granular or liquid) in the early to mid spring. Acelepryn contains the active ingredient Chlorantraniliprole which is also in Scott’s GrubEx. 

The next best option, though may be phased out soon, is Merit (Imidacloprid). There has been reports of a breakthrough in Imidacloprid – meaning the insects have developed a resistance to the chemical. For this reason, we highly suggest Acelepryn.

Signs Of Grub Worms In Lawn

Grubs are active in the summer month. The most telling signs of grubs in your lawn will be irregular dead brown patches of grass (not to be confused with brown patch fungus). This is due to the grub worm larvae munching on the roots of the grass. These patches of dead grass will be easily peeled back like a carpet or doormat. At this point, the grass is dead and will not come back. You could attempt spoon feeding starter fertilizer and micronutrients such as Green Lawn & Turf, but core aeration and overseed is most likely in order to restore the lawn.

Below are some images of the aftermath of grub damage.

How to Kill Grubs

If you missed the window to prevent white grubs and are seeing visible grub worm damage, you need a fast-acting curative. The best product to use is Dylox. The active ingredient Trichlorfon needs to be watered in immediately to begin activating. Once it’s in the soil and taken into the roots, Dylox quickly kills grubs then degrades quickly.


Grub worms can do extensive, irreversible damage. If you plan on having a healthy, vigorous green lawn, be sure to stay ahead of these pests by applying a preventative application of Acelepryn in the spring. If you or your neighbors have had a history of grub problems in the past, this is a very important step.

If you missed the window or are noticing active grub damage, use a fast-active grub killer – we highly recommend Dylox. Once the grubs have been knocked down, you can begin repairing and reseeding the dead areas.

Frequently Asked Questions

What are the best products to kill grubs in lawn?

The best products to kill grubs in your lawn contain the active ingredients Carbaryl (Sevin)
or Trichlorfon (Dylox). Products like Jonathan Green Grub & Insect Control contain Imidacloprid & Lambda-Cyhalothrin which can be used to kill grubs, but only in the early larvae stages, but is best used as a preventitive.

What are the best products to prevent grubs in lawn?

The best products to prevent and control grubs in your lawn contain the active ingredients Imidacloprid (Merit, Jonathan Green), Chlorantraniliprole (GrubEx) or Thiamethoxam (Meridian). These products last 3-4 months and should be applied in the beginning of June to help prevent grub worms.

How do grubs damage your lawn?

Grubs are the larvae of the Japanese beetle (June bug). As the larvae hatch, they begin to eat the roots of your grass – not the grass blades themselves (those are chinch bugs). As the grubs finish eating the roots, they move outwards to more roots. This causes the irregular dead brown patches of grass.

What are grub worms?

Grubs are most commonly the larval stage of the European chafer, June beetle (June bug) and Japanese beetle. Adult beetles lay their eggs in the early summer in June and July; larvae hatch and begin to eat the grass roots throughout the summer and into early fall; grubs reemerge in the spring overwinter, pupate in late May and into June, and the lifecycle begins all over again.


Leave a Comment